Use file metadata with Cloud Storage on Android

After uploading a file to Cloud Storage reference, you can also get and update the file metadata, for example to view or update the content type. Files can also store custom key/value pairs with additional file metadata.

Get File Metadata

File metadata contains common properties such as name, size, and contentType (often referred to as MIME type) in addition to some less common ones like contentDisposition and timeCreated. This metadata can be retrieved from a Cloud Storage reference using the getMetadata() method.

Kotlin

// Create a storage reference from our appvalstorageRef=storage.reference// Get reference to the filevalforestRef=storageRef.child("images/forest.jpg")
forestRef.metadata.addOnSuccessListener{metadata-> // Metadata now contains the metadata for 'images/forest.jpg'}.addOnFailureListener{// Uh-oh, an error occurred!}
StorageActivity.kt

Java

// Create a storage reference from our appStorageReferencestorageRef=storage.getReference();// Get reference to the fileStorageReferenceforestRef=storageRef.child("images/forest.jpg");
forestRef.getMetadata().addOnSuccessListener(newOnSuccessListener<StorageMetadata>(){@OverridepublicvoidonSuccess(StorageMetadatastorageMetadata){// Metadata now contains the metadata for 'images/forest.jpg'}}).addOnFailureListener(newOnFailureListener(){@OverridepublicvoidonFailure(@NonNullExceptionexception){// Uh-oh, an error occurred!}});
StorageActivity.java

Update File Metadata

You can update file metadata at any time after the file upload completes by using the updateMetadata() method. Refer to the full list for more information on what properties can be updated. Only the properties specified in the metadata are updated, all others are left unmodified.

Kotlin

// Create a storage reference from our appvalstorageRef=storage.reference// Get reference to the filevalforestRef=storageRef.child("images/forest.jpg")
// Create file metadata including the content typevalmetadata=storageMetadata{contentType="image/jpg"setCustomMetadata("myCustomProperty","myValue")}// Update metadata propertiesforestRef.updateMetadata(metadata).addOnSuccessListener{updatedMetadata-> // Updated metadata is in updatedMetadata}.addOnFailureListener{// Uh-oh, an error occurred!}
StorageActivity.kt

Java

// Create a storage reference from our appStorageReferencestorageRef=storage.getReference();// Get reference to the fileStorageReferenceforestRef=storageRef.child("images/forest.jpg");
// Create file metadata including the content typeStorageMetadatametadata=newStorageMetadata.Builder().setContentType("image/jpg").setCustomMetadata("myCustomProperty","myValue").build();// Update metadata propertiesforestRef.updateMetadata(metadata).addOnSuccessListener(newOnSuccessListener<StorageMetadata>(){@OverridepublicvoidonSuccess(StorageMetadatastorageMetadata){// Updated metadata is in storageMetadata}}).addOnFailureListener(newOnFailureListener(){@OverridepublicvoidonFailure(@NonNullExceptionexception){// Uh-oh, an error occurred!}});
StorageActivity.java

You can delete writable metadata properties by passing null:

Kotlin

// Create file metadata with property to deletevalmetadata=storageMetadata{contentType=null}// Delete the metadata propertyforestRef.updateMetadata(metadata).addOnSuccessListener{updatedMetadata-> // updatedMetadata.contentType should be null}.addOnFailureListener{// Uh-oh, an error occurred!}
StorageActivity.kt

Java

// Create file metadata with property to deleteStorageMetadatametadata=newStorageMetadata.Builder().setContentType(null).build();// Delete the metadata propertyforestRef.updateMetadata(metadata).addOnSuccessListener(newOnSuccessListener<StorageMetadata>(){@OverridepublicvoidonSuccess(StorageMetadatastorageMetadata){// metadata.contentType should be null}}).addOnFailureListener(newOnFailureListener(){@OverridepublicvoidonFailure(@NonNullExceptionexception){// Uh-oh, an error occurred!}});
StorageActivity.java

Handle Errors

There are a number of reasons why errors may occur on getting or updating metadata, including the file not existing, or the user not having permission to access the desired file. More information on errors can be found in the Handle Errors section of the docs.

Custom Metadata

You can specify custom metadata using the setCustomMetadata() method in the StorageMetadata.Builder class.

Kotlin

valmetadata=storageMetadata{setCustomMetadata("location","Yosemite, CA, USA")setCustomMetadata("activity","Hiking")}
StorageActivity.kt

Java

StorageMetadatametadata=newStorageMetadata.Builder().setCustomMetadata("location","Yosemite, CA, USA").setCustomMetadata("activity","Hiking").build();
StorageActivity.java

You can store app-specific data for each file in custom metadata, but we highly recommend using a database (such as the Firebase Realtime Database) to store and synchronize this type of data.

File Metadata Properties

A full list of metadata properties on a file is available below:

Property GetterTypeSetter Exists
getBucketStringNO
getGenerationStringNO
getMetadataGenerationStringNO
getPathStringNO
getNameStringNO
getSizeByteslongNO
getCreationTimeMillislongNO
getUpdatedTimeMillislongNO
getMd5HashStringNO
getCacheControlStringYES
getContentDispositionStringYES
getContentEncodingStringYES
getContentLanguageStringYES
getContentTypeStringYES
getCustomMetadataStringYES
getCustomMetadataKeysSet<String>NO

Uploading, downloading, and updating files is important, but so is being able to remove them. Let's learn how to delete files from Cloud Storage.